Method of and arrangement for receiving short waves



April 13, 1937- M. VON ARDENNE 2,077,290

METHOD OF AND ARRANGEMENT FOR RECEIVING SHORT WAVES Original Filed Feb.5. 1934 MMQM Patented Apr. 13, 1937 v UNITED STATES METHOD OF ANDARRANGEMENT FOR RECEIVING SHORT WAVES Manfred von Ardenne,BierlimiGermany V Original application February 5, 1934, Serial No.709,707. Divided and this application April 15,

o 1936, S3erial No. '74,441. In Germany February The present inventionrelates to an electronic tube for rectifying short waves and is adivision of application, Serial No. 709,707, filed February 5, 1934.

the same control potential when normal radio waves are rectified.

By careful investigation of the frequency dependency of the efiiciencyof the rectifier the applicant has been able to ascertain the reasonsfor the low efiiciency not occurring in the normal radio frequencyrange, and to find means for remedying the same.

Experiments of this nature may be conducted in such fashion that one andthe same highfrequency amplitude is conducted to a tube rectifyingconnection system at a frequency varied between i=3 meters and 200meters, the potential rectifying eifect is measured in the anodecircuit. By such measurements the applicant has found that therectification of short waves is considerably better if relativelypowerful ourrents are efiected in the rectifier circuits. .Ac-

cording to the invention, this is effected by employing smallresistances in the anode circuit.

Experiments have provided the following results:

In the range of the frequencies below a wave length of 30 meters thesensitiveness decreases in the case of anode bend rectification with theuse of grid leakage resistances in the usual order of 10 ohms andreaches the relatively lowest value at 7 meters. Also in the case ofanode bend rectification with high anode resistances of approximately500,000 ohms there is a decrease in the sensitiveness in the case ofwaves below approximately 20 meters. Now a considerably better effectmay be obtained in accordance with the invention by operating in thecase of anode bend rectification with anode resistances which areconsiderably smaller than those employed with good results for normalfrequency.

The electrons which in the case of anode bend rectification with highanode resistances form the anode current possess speeds which areusually very low, the control potential possessing a value in the orderof approximately 1 volt. The

electrons do not assume higher speeds until the electrons have passedthe grid, i. e. at a time when control has already taken place. As longas the electron speeds are so small, the time in which an electron ispassing from cathode to anode is such that the same is greater, or may 5be greater, than the period, for example, of a 7-meter oscillation. Fromthe influence exerted by the duration of passage of the electrons, whichcannot be ignored in rectification, there results. the frequencydependency of the rectification in 0 the frequency range above stated.

After having found out the reasons for this frequency dependency inaccordance with the invention for improving the efficiency of theanode-bend rectification for short waves there 15 is used a relativelysmall anode resistance in the order of 10 ohms, which causes the fullanode I potential to be applied to the anode practically continuously;further, tubes having a relatively small amplifying factor =10 are used.in this 20 connection the resting or working point is transferred as faras possible near to or in the upper bend in the characteristic of theanode current. The object of the arrangement according to the inventionis to perform the control in such fash- 25 ion by the high-frequencypotential to be rectified that electrons having as far as possible ahigh speed are covered by the control, and that the control takes placein a narrowly confined space surrounding the grid. I 0

When employing connection systems having resistances with the value andarrangement as set forth in accordance with the invention it is possibleto produce receivers for short waves, and more particularly waves ofless than 10 meters 35 (preferably for television purposes), which havean adequate sensitiveness, even without inter mediate frequency.

In the drawing there is shown by way of an example a form of embodimentof receiving and 40 rectifying systems for anode-band rectification, theconnecting elements in the working circuits having the values accordingto the invention. The single parts are the rectifier tube l with thecathode 2, the grid 3 and the anode 4. 45

Between the grid and the cathode there is provided the oscillatorycircuit 5, which comprises the self-inductance 6 and the variablecapacity 1.

In the outer anode circuit there is connected 50 a resistance II which,in accordance with the invention, is in the order of 10 ohms. Couplingis performed through the medium of a condenser I 2. To accomplish atransfer of the working point to the upper bend of the characteristic 5510 fication factor, the anode potential being sulficient to make thetime the electrons take to pass the distance between the electrodesshorter than a period of the high frequency to be rectified.

2. In a tube for rectifying short waves, more 15 particularly for wavesof less than 10 meters,

using anode bend rectificatioma cathodaa grid and an anode, said anodeconnected to a source of high positive potential over a relatively smallanode resistance, said tube having an amplification factor smaller than10, the anode potential being suflicient to make the time electrons'taketo pass the distance between the electrodes shorter than a period of thehigh frequency to be rectified.

3. In a tube for rectifying short waves, more particularly for waves ofless than 10 meters, using anode bend rectification, a cathode, a gridand an anode, said anode connected to a source of high positivepotential over a relatively small anode resistance, said tube having asmall amplification factonthe anode potential being sufficient to makethe time the electrons take to pass the distance between the electrodesshorter than a period of the high frequency to be rectified, a highpositive grid bias suflicient to obtain a working-point in the upper endof the plate currentgrid voltage characteristic.

MANFRED VON ARDENNE.

